How Much Caffeine Is Actually in Your Cup?

Ask ten people whether an espresso or a mug of filter coffee has more caffeine, and you'll get ten confident, contradictory answers. Here's what's actually going on.

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Concentration versus volume

Shot for shot, espresso is far more concentrated than filter coffee, roughly 60–75mg of caffeine packed into a single ounce. But an espresso shot is small, around 30ml. A standard mug of filter or French press coffee is 200–250ml and typically carries 90–120mg of caffeine, sometimes more depending on strength.

So the honest answer is: your morning mug almost certainly has more total caffeine than a single espresso, even though the espresso tastes and feels stronger. It just comes down to how much liquid you're actually drinking.

What actually moves the number

• Bean type. Robusta carries roughly double the caffeine of Arabica, gram for gram, which is one reason it doesn't taste as good, but does hit harder.
• Roast level. Contrary to popular belief, dark roasts don't have meaningfully more caffeine than light roasts. Caffeine is fairly stable through the roasting process, it's more about how you measure your dose.
• Grind and brew time. A longer contact time between water and grounds, like a French press steep or a cold brew, extracts more caffeine, not just more flavour.
• Dose. More coffee per cup means more caffeine, obviously, but it's the one variable most people never actually control, since they're not weighing it.

How long it actually stays in your system

Caffeine has a half-life of roughly 5–6 hours in most healthy adults, meaning half of whatever you drank at 2pm is still active in your bloodstream around 7–8pm. That's the real reason a mid-afternoon flat white can wreck your sleep even if you feel fine straight after dinner, you've still got a meaningful dose circulating come bedtime. If you're sensitive to it, a common rule of thumb is to stop drinking coffee at least 8–10 hours before you want to sleep.

If you want to actually see that half-life playing out rather than just take our word for it, a sleep tracker is the simplest way to do it. It won't diagnose anything, it just shows you the dip in sleep quality on the nights you had a late coffee versus the nights you didn't, which tends to be more convincing than any half-life chart. The Xiaomi Smart Band covers the basics well without much outlay. If you want to go further, WHOOP is genuinely the most sleep and recovery-focused wearable on the market, worth knowing upfront that it comes bundled with an ongoing annual membership rather than being a one-off purchase, which is the trade-off for the extra depth.

A rough guide

Most reputable estimates put a standard mug of filter coffee around 95mg of caffeine, a single espresso shot around 63–75mg, and a double around 125–150mg. Cold brew, because of its long steep time, can come out anywhere from comparable to noticeably higher, depending on how it's made. General health guidance suggests most healthy adults can comfortably handle up to around 400mg a day, though that threshold is lower for some people, so it's worth checking with a doctor if you're unsure where you sit.

Whichever way you take it, knowing roughly what's in the cup helps you actually manage your own intake, rather than guessing based on how strong it tastes. Both Lekker Brew and Bliksem Brew are medium roasts, so if you were hoping to manage caffeine by roast level alone, that particular lever won't do much, brew method and dose matter far more.